Chemical treatment of finely divided solids



May 13, 1952 w. L. wr-:lDMAN ET A1.

CHEMICAL TREATMENT OF' FINELY DIVIDED SOLIDS Filed April '7, 1948 POWDERED CLAY Patented May 13, 1952 CHEMICAL TREATMENT OF FINELY DIVIDED SOLIDS Walter L. Weidman, Woodbury, N. J., and Hubert A. Shabaker, Media, and Edward B. Cornelius, Swarthmore, Pa., assignors to Houdry Process Corporation, Wilmington, Del., a corporation of Delaware Application April 7, 1948, Serial No. 19,456

(Cl. 25Z-439) Claims. 1

The present invention relates to improved methods for chemical treatment of solid materials such as clay and other minerals in finely divided or powdered form with gaseous materials which react therewith or with components thereof. One of its particularly valuable applications is the treatment of finely divided or powdered clay and other mineral products by methods including sulfidation, for example, in the preparation of modified powder products of the type particularly useful as or in catalysts for hydrocarbon conversion operations.

In copending applications Serial Nos. 644,423 and 644,426 (iiled January 30, 1947 jointly in the names of Hubert A. Shabaker, George Alexander Mills and Ruth C. Denison, now issued respectively as U. S. Patents Numbers 2,466,048 and 2,466,051) methods are described for the production of modified clay masses providing catalysts of unique properties, by treatment of ironcontaining clays with sulfiding gases at elevated temperature followed by the removal of the iron sulfide thus formed. The novel contact masses thus obtained are changed in physical and chemical properties and demonstrate important advantages as catalysts, including exceptionalI stability in cracking and in treating petroleum stocks of high sulfur content.

In a copending application of Hubert A. Shabaker, Serial No. 6,722, filed February 6, 1948, certain improved methods for suldation of solid materials are described employing a treatment of at least two stages, wherein in an initial stage the material, such as clay or other mineral, is heated to desired high temperature for the suliidation reaction by Contact with an essentially inert gaseous medium carrying a comparatively small quantity of active gaseous sulfide, such as HzS or CS2, the thus heated and partially sulded clay being subsequently contacted for a comparatively short time with concentrated sulding gas to perfect or assure completion of the sulfiding reaction. The sulded clay is subsequently cooled and subjected to acid-leaching, principally effecting thereby removal of the iron suldes formed. By this operation efficient and uniform sulfiding of the clay is obtained using only fairly small amounts of active sulding gas for reaction with the iron content of the clay, affording, among other advantages, the best economy in the use of the sulfiding gas. The resulting sulded clays are capable of being easily leached with acdto Vprovide modified clay products of low iron content and of uniformly high and:- stable catalytic activity.

One specic procedure described in said last named copending application involves movement of the solid material downwardly and countercurrently to the treating gas in each of several treating stages. That particular procedure offers its greatest versatility and flexibility when the individual particles of solid arevof relatively high mass, especially when they are relatively coarse, for example, granular or molded. Somewhat less versatility and flexibility, particularly with respect to the ratios of gaseous or solid materials are realized when the gravitating solid material is in finely divided or powdered form.

Another method for contacting finely divided or powdered solid with gases or vapors involves passage of the gas phase through a mass of the solid under such conditions including velocity that the solid is iiuidized, that is, maintained in relatively dense form and turbulent suspension within the gas. In counter-current flow systems such as that mentioned above where the temperature of the downwardly flowing solid gradually approaches the inlet temperature of the upwardly owing gases, and, when sufficient contact is pror vided, these temperatures become substantially the same at the lower end of the treating vessel.

`In contra distinction to this desirable feature of counter-current flow, when gas and finely divided solid at different temperature levels are brought together to form a fiuidized mass, layer or bed, the mixing and heat exchange results in a suspension or mixture at equilibrium temperature intermediate that of the entering gaseous and solid components. In reaching this equilibrium temperature certain portions of the powdered solid reach temperatures above that equilibrium level. The greater the extent to which the temperatures of the solid is changed, the greater is the difference between the equilibrium and gas temperatures. When treating temperatures are high, as of the order of 1000 to' 1500"V F., supply of the still hotter treating gas involves major problems of design and operation of heating equipment therefor. Moreover. Vbecause of the turbulent nature of fluidized masses certain of thepowdered material remains within the treating zone for longer than the average solid residence time.

It is thus apparent that in treatment with hot gases of relatively cool solids whose desired catalytic or other adsorptive properties are impaired or destroyed by excessive temperatures and by residence for prolonged or uncontrolled periods at such temperatures, as is the case with clays. and otherjminerals, the fiuidized bed ytechnique presents inherent disadvantages. These disadvantages or difliculties are minimized or even overcome by utilization of a unique multi-stage process and system with which the present invention is concerned.

In practice of the present invention sulfidation of finely divided solid materials such as ironcontaining clays and other minerals, is eiected by heating the solid material to desired or optimum reaction temperature range in a plurality of separate heating stages of successively increased temperature, the solid material being maintained by suspension in heating and treating gas as a dense turbulent luidi'zed mass, which gas enters each stage at a temperature higher than that of the solid material entering that stage. The heating and treating gas thus utilized contains in dilute concentration therein active Ysulfiding gas so that while bringing the solid material to desired maximum reaction temperature, at least partial suldation of the solid material is initiated to desired etent. In accordance with a preferred aspect of the invention, the hot suliided solid material is further contacted with cooler concentrated sulfiding gas for a relatively short time to perfect or complete the suldation of any possible material not fully reacted in the previous operation, thereby assuring uniformity of treatment without unduly prolonging the reac- Y tion time, and thereby utilizing the capacity of the equipment to best advantage.

In the preparation of finelymdivided or powdered modied clay products of low iron content,

Y and of improved catalytic properties, which is one of the principal purposes of the invention, temperatures in the order of 12200-1500o F., preferably from about 1300-1450" F., are employed, and thesulfided clay is ultimately treated, as with dilute mineral acid, to remove the formed iron suliides. A preferred acid treatment comprises the use of aqueous mineral acid of 5 to 15% concentration over a period of 8 to 24 hours or more at room temperature or above, as up to about 180 F. Y

The novel features of the invention are not limited in their application to suldation reactions, but can be advantageously employed in other operations wherein iinely divided solid materials are reacted with gaseous fluids at elevated temperatures, particularly in instances where the reaction temperatures desirably employed must be carefully controlled to avoid any detrimental effects of overheating the material. Processes involving chlorination of mineral materials such as iron containing clays and the etching of siliceous mineral materials with corrosive gases such as hydrogen fluoride are noteworthy examples.

The invention will be more clearly understood from the description which follows read in connection with the accompanying drawings illustrating typical arrangements of continuous treaters adapted for use in practice of the invention. Figure l is a View of such a treater in vertical cross section, and Figure 2 is a partial View of a modification thereof.

'Ilo simplify description of the principle of operation, the apparatus is hereinafter described in connection with its use in suldation of finely divided clays or other iron containing minerals, although it will he understood that the invention is not to be construed as iiinited thereby.

In the illustrated embodiment of Figure l, there is shown generaily ar upright Vchamber-ery reactor" i 'which is preferably 'cylindrical at 'its upper sectionforrned' by the `lateral 'wail but may be of other desired shapes. The wall 2, because ci the high temperature of the suliide or other corrosive gas in this section is preferably formed of a ceramic material or other corrosionresistant and insulating material at least throughout that section of its length coming into contact with high temperature corrosive gas, as at temperatures above about 906 F. For reinforcing the structure, a shell of metal or other suitable material of construction may be employed outside of the wall 2, as illustrated at 3.

rlhe iinely divided clay or other solid material to 'oe treated is introduced into the reactor at the top thereof by suitable conveying means which may comprise, as shown, a screw conveyor I fed from any suitable source of supply (not shown) as a bin, hopper, pneumatic conveyor or the like communicating with the inlet of conveyor 4.

At its lower section the wall 2 is flared inwardly to provide a thickened wall portion 2a.. An annular slot 5 oi suitable length, as will be hereinafter more fully explained, is provided in the thickened wall portion 2a. rIhis slot provides a channel which communicates with a feed line t, through which the heatingV gas is introduced into the reactor, said gas flowing upwardly through the annular slot 5 to a mixing lzone VM below the primary treating section. The primary treating section is divided into separated treating zones P1 through P7 by horizontal perforated partitions such as shown at yI3, 9, It, II, I2 and I3, which partitions are also preferably formed of ceramic or other4 material resistant to the suldinggas at elevated temperature. The number of such partitionswill be governed by the size of the unit and the desired temperature gradient within the reactor.

Below the inwardly flared portion of the wall 2 and Vextending through substantially its entire length, the thickened wall portion forms the lateral wall of the secondary treating section which is likewise divided into separate treating zones as Si, S2, S3; by horizontal partitions I5, IB and Il, which desirably are also formed of ceramic material. Concentrated suliding gas containing for instance I-IzS or CS2, is introduced into the second-ary treating section and below Si, by a line such as is shown at I8, the gas passing upwardly through the perforated partitions 15, I6 and I and entering thereabove the mixing zone M where it admixes with the hot gas introduced through line 6 and annular slot 5. The mixture of the concentrated gas with the hot gas thus formed in the mixing zone M, passes upwardly through the perforated partitions l, 8, Si, Iii, I I, I2, and I3 to be discharged through a conduit as shown at 2li, which may be provided with means for separating out entrained solid materials (not shown) such as electrostatic precipitators or cyclones.

The number oi partitions in the lower sectionis suliided by the gaseous suliide component ofY such gas. As a result of continuous addition of starting solid material by the conveyor 4, the level ofthe fluidized bed above the partition I3 will be raisedtoabove the height of the vertical conduit `2 I passingV throughsuch partition. `Solid materials from the upper level of/.the 'bed-Will therefore overflow into the conduit 2| and downwardly therethrough to form a layer above the partition |2 at the next lower level, which layer will similarly be fiuidized by entering gases flowing upwardly through the partition |2 and again overflow above the upper level of the layer into a similar conduit 22, and so forth; the solid material thus passing downwardly from layer to layer in the primary treating section through the respective conduits 23, 24, 25, 26 and 21.

Above the partition in the secondary treating section, the already heated and partially treated material discharging from conduit 21 into zone Sa will similarly be fluidized by entering gas therein and with continuous addition of solids will overflow into the next succeeding zones S2 and S1 by conduits 28 and 29 respectively. The solid material in the respective layers above the partitions |5 and IG in turn being maintained in uidized state by the gases passing upwardly through said partitions. In the manner described accordingly, the solid material will have been heated and treated in passing in contact and in countercurrent relation with the several upwardly flowing introduced gases.

The treated solid material is ultimately discharged through a conduit 39 provided with a gate valve or suitable flow control means as shown at 3|, by overflowing above the partition |5 through a conduit 32 into a cooling section C and from said cooling section by overflow into the conduit which extends upwardly above the lower terminus of the conduit 32. Cooling is effected by indirect heat exchange or other known means such as by the provision of a liquid containing jacket in the space between the walls 33 and 31| through which space water or other desired cooling fluid is circulated in known manner as by lines 35 and 36.

To prevent discharge of sulfide gas with the solid materials through conduit 30 and to assure upward flow of the concentrated sulfide gas introduced through line I8, an inert seal gas is introduced at the bottom of the cooling section C, as by means of a line 31, at a pressure slightly above that present at the point of introduction of the concentrated sulfiding gas through line |8, thereby opposing downward flow of the sulfidlng gas. Only small volumes of Aseal gas are required as in the order of 1 to 2% of the volumetric rate at which the heating gas is introduced through line 5.

In the modified embodiment illustrated in Figure 2, the admixture of the concentrated sulfiding gas and the introduced he-ating gas takes place within the zone P1 of the primary treating section. The heating gas is introduced through a line 5B communicating with a channel or conduit 5| provided or formed in a ceramic block 52 extending from the reactor la below the partition "la, which block may be reinforced by an outer metallic shell, as shown, formed integrally with or securely attached to the shell 3.

In the modified embodiment as illustrated in Figure 2, the solid material overflowing from zone P1 enters a conduit 53. This conduit is formed of corrosion resistant material and is of suitable diameter for handling a sufficient volume of concentrated treating gas without necessitating gas flow rates at high enough velocities to prevent gravitation of solid materials through the conduit counter to the upwardly flowing Agas therein introduced as hereinafter described.v 4 The conduitA 53 ls contiguous with a channel 54 formed in a ceramic block 55, the

The ceramic block is cut in as shown at 59 and 50 to provide annular gas intake channels in direct communication with and surrounding the channel 54. Concentrated sulfide gas is introduced into the annular channel 55 by means of a connecting feed line 6|. An inert gas, operating as a seal gas, is introduced through line 62 at a slightly higher pressure to direct upward flow of gas through the channel 54 and conduit 53. The lower edges of the cut away portions at 59 and 60 are at a suihciently steep angle to overcome any tendency of flowing solids to repose thereon.

The rate of flow of the gases in channel 54 is such as to provide hindered settling of the solid material descending through such channel. The quantity of sulfiding gas that can be introduced into the channel 54 as through line 5|, under these conditions is substantially less than that which can be employed in the alternate construction illustrated in Figure 1. In using the embodiment of Figure 2, accordingly, it is recommended that a larger quantity of active sulfide gas be admitted with the heating gas entering through line 53, so that the active sulfide gas is in sufhcient concentration to provide within the primary treating section an amount of such sulfide several times the equivalent of the theoretical iron content of the clay fed thereto. The sulfide gas may be admitted through a line B3 in communication with channel 5| through which the heating gas is flowing.

The sulfided material is further cooled by continuously being discharged from the channel 54 into a cooling section C similar to that shown in the embodiment of Figure 1. The cooled product is discharged from the cooling zone through a conduit provided with a gate valve or other suitable flow control means as shown at 65.

In the apparatus thus far described, and other types of apparatus that may be substituted, pro- Vision is thus made for securing the desired mixture of sulfiding gas and heated carrier gas constituting the dilute treating gas for the first stage treatment, as a result of the flow or diffusion of a portion of the concentrated sulfide gas from the latter treating stage; the construction being such as to minimize channelling of gas. It is preferred in practice, however, even with the use of the embodiment of Figure 1 to further assure sulfidation of the clay uniformly across the transverse section of the reactor, to add at least a small portion of sulfide gas with the hot carrier gas directly introduced into the reactor in the rst stage; for example, by admission of the carrier gas together with the desired portion of sulding gas through line 6 in the illustrated apparatus.

The concentrated sulfide gas introduced in the second stage, need not be at a high temperature. Since the clay is already heated to required temperature as a result of the first stage treatment, and only small amounts of total gas and a comparatively short time of treatment employed for the second stage, the concentrated gas may be introduced at ordinary temperature, including room temperature or lower. In fact, reduction in temperature of the clay during the second stage suldation treatment may be -advantageous from the standpoint of assisting cooling thereof.

The heating gas serving also as the carrier gas for the dilution of the H25, CS2, or other active sulding gas or vapor, must be essentially inert; that is; it mustbe free from other constituents in amounts which would interfere with the sulfldation reaction or be harmful to the clay or the catalyst prepared therefrom. Commercial nitrogen is an example of a gas substantially fulfilling these requirements.

Another essentially inert heat carrier gas, which is comparatively cheap and readily made available, is a specially processed or prepared flue gas, which may be obtained for instance by the controlled combustion of a fuel. VGaseous fuels are preferred because of easier control of combustion; examples of such gaseous fuels which may be burned to provide flue gas, include propane, and domestic heatinggas. YSuch flue gases from commercial propane, for instance, can be readily prepared free of oxygen, but would then contain components such as Water vapor, CO2, and generally small amounts of CO and Hz in addition to nitrogen.

Although in a single stage Vtreatmfmt employing dilute sulfide gas, the quantity of carbon dioxide that may be present in the `carrier gas is limited because of the adverse effect of large quantities of Carbon dioxide on the suldation reaction and on Vthe subsequent facility of leaching of the clay, in following the two stage treatment of the present invention yand employing a final treatment with concentrated sulding gas, such adverse effect of substantial quantities of CO2 is considerably reduced or substantially eliminated. Effective sulding followed by good acid leaching can be obtained by initial treatment with flue gas compositions containing 12 to 15% or more (by volume) CO2 and only very small concentrations lof sulfide gas, in the orderof 0.57% to 1% HzS (of the total volume of treating gas), followed by treatment of the clay for a short period in more concentrated sulfide gas containing from about 25 to 100% sulfide by volume of total concentrated treating gas. The totalquantity of sulfide employed need be only in slight excess of the theoretical equivalent of the iron content of the clay, but is preferably several times the equivalent.

During the first stage treatment` wherein the clay or other finely divided mineral material is being heated to desired reaction temperature, comparatively large amounts vof heating gas are required. The rate of admission of heating gas has no noticeable effect on the `suldation reaction, provided it is high enough to effect fluidization Yof the several catalyst beds of the series and provides sufficient heat to bring the solid, materials to desired reaction temperature. After the solid material has been heated to the desired temperature for suldation, only about one half hour or less may be lrequired for obtaining lcompletereaction with the iron content of the clay;

nevertheless, it will often be found advantageous to retain the clay within about 100 F. of maximum temperature attained for at least one hour and'preferably for about 2 to 5 hours before subjecting the clay to the nal cleanup treatment with the concentrated sulding gasp. Extending the time of treatment beyond the indicatedtime, has not, been found .to provide any particular advantage; on the other hand.; has' any detrimental effect been noted. The treatment with the concentrated sulfide gas in the secondary or cleanup section need be conducted for only .a comparatively short time asin the order of only several minutes. `Even'wth concentrationsof sulde gas as low asabout 25%no particular advantage appears for extending the residence time of the solid materials in the secondary treating section beyond about 10 to 30 minutes.

The dimensions of the reactor and the relative-size and number of beds in the primary and secondary treating sections as well as the rate and volume of admission of the several gases, it Will be understood, will be controlled by the indicated time factors correlated with the quantity of material being handled. Also depending upon the degree of improvement sought'and the nature of the starting material, more or less than the illustrated number of beds may be provided in the primary as well as in the secondary treating sections.

The following example is illustrative of a practical cperation of the invention employing the illustrated apparatus of Figure 1. An acid activated sub-bentonite montmcrillonite clay, Super Filtrol, (containing about 2.0% by weight liezCls on a calcined clay basis) is furnished in finely divided form by milling or'crushing and screening to desiredsize, as that having a particle size designed for use in conducting operations employing fluidized bed technique (as of about 50 to 300 mesh average particle size). The

heating or carrier gas, which is also used as the o seal gasV in this instance, is a flue gas obtained by drying the combustion product of propane burned in air under controlled conditions to obtain a composition substantially free of Oxygen. This composition dried to contain only a trace of water, typically contains 13.1 volume percent CO2, 1.0% and 1.7% CO. A flue gas of this composition has a Ycalculated density of about .078 lb. per cu. ft. at room temperature F.) and an average molecular Weight of about 29.6.

The inert carrier gas is introduced through line 6 at a temperature of approximately 1450 F. and at a rate of about 1.3 to 1.4 lbs. of gas per lb. of clay introduced per hour corresponding to 16.7 to 18 cu. ft. of such gas per hour (60 F.). The portion of the flue gas admitted ,through line 31 to operate as sea1'gas,.constitutes about 1 to 2% of the volumetric rate at which the lheating gas is introduced through line E. The total quantity of sulding gas employed is'in excess of the stoichiometric equivalent of the iron' content of the clay or on a Weight for weight basis, about 1.82 lbs. of hydrogen sulfide per lb. of iron compounds contained in the clay, calculated as F6203. This quantity of hydrogen sulde is provided by the use of 100% H2S admitted through line I8 at a rate to provide equal volumes of inert gas and sulding gas in the zone immediately below partition I5, forming a sulding gas of 50% volume .Concentration which passes through the several beds in the secondary treating section comprised of the fluidized beds below mixing zone M. A small amount of hydrogen sulfide cornprising 1 to V2% by volume of the inert gas is introduced also directly into the iirst treating stage in admixture with the hot inert gas through line 6 and annular slot 5.

HAt the flow rates indicated in this example, the residence time Qf the Sulde material in .0f 17.1.05 eY'SQ @QCS .CQlSltllllg .the Pimay 'ff-'" its section-is about 1.6 .hours- Seven web beds being employed, the total residence time in the primary treating section during which the clay is heated to required temperature and initially sulded amounts to about 11.2 hours. The size of the secondary treating section is such as to provide a total of about 0.5 hour for passage of the solid material through the three beds of the illustrated embodiment; constituting about 0.17 hour residence time in each bed. In the cooling zone the clay is cooled to desired discharge temperature below about 80G-1000" F.

Following discharge from the cooling section of the treater, the clay is further cooled to required temperature for acid treatment, which treatment is carried out, in this instance, at room temperature employing dilute mineral acid such as aqueous hydrochloric acid for a period of 24 hours, the acid being changed once during the treating period. Subsequent washing with water and drying completes the operation. In this manner there are obtained contact masses of improved catalytic properties having about 0.1% or less by weight of total iron compounds calculated as FezOs.

If it is desired to calcine the obtained modified clay and stabilize the catalytic activity thereof before charging the same to a hydrocarbon conversion operation, this may be accomplished by treatment at temperature above about 800 F. in air, steam, or mixtures of these, employing one or more fluidized beds of the type already described for the initial sulding operation.

In the illustrated embodiment it will be seen, that heating of the clay is effected by direct exchange with the introduced heating gas, the temperature of the clay progressively increasing from room temperature (as it is introduced into the reactor by conveyor means 4) to about 1400 F. (in the lowermost section of the primary treating section), while'the gas entering through line 6 is progressively cooled in passing upwardly from zone to zone from its initial temperature of about 1450 F. to about 680 F. at its point of discharge. The various temperature changes undergone by the clay and gas are illustrated by the following table:

In primary stage zones With the type of clay in the example, although lower maximum temperatures can be employed, for the production of catalysts of lowest residual iron content and maximum catalytic activity, suldation at about '1350-1400 F. is recommended.

It will be understood that the seal gas need not necessarily be of the same composition as the heating gas, but the use of the same composition adds to the simplicity of the operation. The desired concentration of sulfiding gas in the secondary treating section is obtained by dilution of or other concentrations of sulfide gas introduced through line I8 with the required quantity of seal gas introduced through line 31.

To obtain good sulfiding action and ready removal by mild acid leaching of the formed iron suliide, the treating gases should be substantially free from uncombined oxygen and from water. A maximum moisture content of 0.2 volume percent of the described :due gas used as a diluent and heating gas is readily obtained by passing such gas over a dessicant such as silica gel.

In the preferred operation hereinbefore described, the concentrated sulde gas from the secondary treating section is permitted to enter the primary treating section for use therein. It will be apparent, that if desired, this gas may be vented from the reactor, and all of the desired concentration of sulfide gas separately furnished for the primary treatment.

In the described manner, iron-containing clay cr other mineral is heated up to required reaction temperature and most, if not all, of the iron content thereof is reacted in the primary treatment during contact with comparatively large volumes of dilute sulfiding and heating gas. The use of such large volumes of gas at the outset of the treatment also serves to rapidly flush from the clay or other mineral, undesirable reaction or calcination products, thereby avoiding or minimizing adverse effects on the treated product and the thus sulded product may then be subjected to` further suldation during a secondary stage of treatment with excellent results, employing only a comparatively small volume of concentrated sulding gas. This subsequent treatment with the concentrated sulflding gas provides a cleanup or equalizing step insuring complete suldation of the iron content of the clay or like and compensating for any irregularities that might be experienced during operation of the previous stage. Such irregularities in operation during the rst stage may result from gas channelling, imperfect mixing or nonuniform mixtures of active sulde and carrier gas, non-uniformity of time of contact due to differences in flow rate of the clay over the cross sectional area of the reactor, or other conditions that might be encountered in practical operation.

The described multi-stage treatment, in addition, results in important economies in heating costs and in total sulding gas. During the initial heating stages relatively small amounts of sulfide gas may be used, and with the embodiment of Figure 1, quantities of sulde even less than theoretically required for complete sulfidation can be utilized. The required further reaction can then be easily accomplished with high concentrations of sulfide gas in a comparatively low bulk volume. The sulfiding reaction is apparently endothermic, and it is therefore advantageous to eiect at least an appreciable part of the reaction in the presence of the heating gas.

The described process is applicable to the treatment not only of sub-bentonite clay of the type described, but also other iron containing clays including raw or acid-treated montmorillonite and kaolin clays and other iinely divided minerals there may be individual variations, the desiredl low residual iron content can be readily obtained under the conditions given; by the use of volumetric gas rates such that there is furnished a concentration of about 1 to 2% active sulfide by volume of total treating gas in the heating and primary treatingY section and 25 to 50% sulfide by volume of concentratedtreating gas in the secondary or cleanup section. In someinstances to obtain the desired low residual iron content more drastic treatment may be required than in the'case oi the illustrated clay; as by the employment of a longer treating time at-the higher temperatures ofy theV range, to about 5 hours, and/or somewhat higher concentrations of sulde'g'as in the ii'rst stage operation, as up to about 3 to v5% of thetotal treating gas employed in .that stage, or up to about fi to 6 times the stoichiometric equivalent cf the iron content of the clay or other material being sul'de'd.

Obviously, many I'nodiicationsl 'and variations of the invention as .hereinbefores'et forth may be madewithout departing from the spirit and scope thereof and, therefore only such limitations should' be vir'riposed as 'are indicated in the appendedclaims, v A

We claim as our invention: Y Y l 1. The process of treating iinely divided solid mineralm'aterial at elevated temperature with gaisV reactive with a component of said mineral materials, which 'comprises continuously feeding CTI Saidfmely divided-Solid mineral material initially Y `for'I'rfedi'r'iisaidprimary`treating zione a gas heated to 'at least" maximum desired reaction i temperature, further' introducing irlftoV saidmixing Zone ay ucoi'centrated, reactive gas lsubstfallitially ller yolunfe thangsaid heated gas, effecting ngof said concentrated reactive gasfwithsaid h'e'afga's in said ni'ixingjzone to form a diluted hot :treating'gash flowing the vdiluted hot treating gas into said final layer at a -rate sufficient lto suspend the solid material in said layer toriorm a denseturbulent fluidized mass,separating dilute hottreating gas from saidfinal layer andflowine the separated'gas to then'ext higher layer to-eriect suspension of the solid materia/l in said layer tofform a'den'sfe turbulent fluidized mass,{l separatingfhotdilute treating gas iromsaid last named layer and successively/ flowing the separated gas inlikemanner to suspend each succeeding higher Alayer and'nally to the iirst and highestY layer formedby the continuous initial feeding of solid minerall materials and thereafterrdischarging separated gas from said highest layer; the tem-V pveraturelof said diluted hot treating gas being reduced in flowing successively through the several layers while the temperature of said solid materialV is increased progressivelyin descent .fromsaid highest layer to said lowermostlayer as a resultvof direct heat exchange in contact between Asaidrdiluted hot` treating gas and said solid material; withdrawing the thus heated and 12 Y treated solid material froms'aid lowerrnost layer oflsaid primary treating zone and contactiri'gthe withdrawn solid Vmaterial directly with concentrated reactive gas introduced at a temperature lower than the temperature of said 'solidv material, said concentratedw reactive gas being owed Vat a rate sufficient to suspend the solid material thus Ycontacted in dense turbulent fluidi'zed con'- dition, separating concentrated reactive gas from Ycontact with said solid material and admitting the separated gas to the aforesaid mixing Zone, continuously withdrawing solid material after contact with the concentrated reactive gas, contive ,gas to form by the admixture said concen-V trated reactive gas hereinbefore specified, and iinally discharging treated Ysolid material in cooled condition. r i i v 2. The process of `tneating iinely divided ironcontaining clayto convert the iron present therein to iron sulde, which comprises continuously introducing such finely divided clay into the upper part oi a primary treating zone tov form a layer of such clay in said zione, flowing into saidy layer a hot gas with velocity sucient to suspend the clay in said layer as adense turbulent luidized mass, said hot gas being at a temperature higher than that of the clay in said Vlayer and said hot gas containing in low concentration active sulding gas, Vcontinuing introduction of nely divided clay to said layer to effect continuous overow of a portion of the clay from said layer, continuously conducting such ove'rowed portion to a lower level in said primary treating zone to form a second layer at that level, contacting said second layerin similar manner with hot gas to suspend the clay in the hot gas and form a dense turbulentiiui'dizedmass of said second layer, continuouslyoverowi-ng clay from said second layer to a next lower layer'and thus from layer to layer through aplur'ality of layers at successively Ilower levels in said primaryV treating `zone, Yeach of the intermediateplilrality of layers being formed into a' dense turbulent fluidized mass by suspension in hot gas passing upwardly into said layer from a next lower layer, said'hotgas entering at a temperature higher than that of the clay contacted thereby'in each of such layers, and the lowermost layer of thejprimarytreating zone being suspended by initialcontact with hot gas introduced into said layer from a mixing zone therebelow, introducing intolsaid mixing zone hot gas from an external source, said gasbeing substantially free of water and uncombined oxygen and being at a temperature not less than the desiredmaximum reaction temperature and in the range of about 1200-1500 F., maintaining a secondary treating zone below said-mixing zone, said secondary treating zone being Vofv substantially smaller cross sectional area throughout than the primary treating` zone, overiiowing finely divided Clav ,from the rlowernios lai/e1: of Suchprimary treatirrlg rione intoisaid secondary treating zone, passing the clay through the secondary treating zone and-discharging the treated clay therefrom, introducing relatively cool concentrated sulflding gas into the bottom of said secondary treating zone'at a temperature below that of theA clay in Sedfzgrle ,flowing theoncentratd sulding gas upwardly throughsaid secondarytreating zone in contact with the clayin said zone, discharging the gaseous eluent at the topcf said secondary treating zone and into said mixing zone for admixture with the hot gas introduced from an external source into said mixing zone, thereby forming hot dilute snlfding gas constituting the aforesaid gas passed through the several layers of clay in the primary treating zone.

3. The process in accordance with claim 2 wherein the clay is contacted with concentrated sulding gas in said secondary treating zone at a Velocity effecting suspension of said clay in the gas as a dense turbulent mass.

4, The process in accordance with claim 2 wherein the concentrated sulding gas comprises at least 25% by Volume of hydrogen sulde in a substantially inert gaseous carrier, and the rates of flow of the concentrated suliiding gas and of the said hot gas from an external source into said mixing zone are controlled to provide in the gas admitted into the lowermost layer of clay in said primary treating zone an amount oi hydrogen sulfide in excess of the theoretical requirement for complete sulfidation of the iron content of the clay.

5. Process in accordance with claim 2 wherein the hot gas introduced from an external source into said mixing zone is at a temperature suiciently high and is maintained in contact with said clay during the several treating stages in said primary treating zone for a time suicient to heat said clay to at least 1200J F.

WALTER L. WEIDMAN.

HUBERT A. SHABAKER.

EDWARD B. CORNELIUS.

EEERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,727,4@1 Parentani Sept. 10, 1929 1,999,773 McMichael Apr. 30, 1935 I 2,388,302 Weyl Nov. 6, 1945l 2,395,198 Schulze Feb. 19, 1946 2,444,990 Hemminger July 13, 1948 2,466,052 Shabaker et al. Apr. 5, 1949 

1. THE PROCESS OF TREATING FINELY DIVIDED SOLID MINERAL MATERIAL AT ELEVATED TEMPERATURE WITH GAS REACTIVE WITH A COMPONENT OF SAID MINERAL MATERIALS, WHICH COMPRISES CONTINUOUSLY FEEDING SAID FINELY DIVIDED SOLID MINERAL MATERIAL INITIALLY INTO A PRIMARY TREATING ZONE TO FORM A LAYER OF SAID MATERIAL IN SAID ZONE, CONTINUOUSLY WITHDRAWING SOLID MATERIAL FROM SAID LAYER TO FORM A SECOND LAYER OF SOLID MATERIAL WITHIN SAID ZONE, SAID CONTINUOUS FEEDING AND WITHDRAWING BEING CONTINUED TO PROVIDE A PLURALITY OF SUCH LAYERS AT SPACED LEVELS IN SAID ZONE, INTRODUCING INTO A MIXING ZONE BELOW THE LOWERMOST FINAL LAYER THUS FORMED IN SAID PRIMARY TREATING ZONE A GAS HEATED TO AT LEAST MAXIMUM DESIRED REACTION TEMPERATURE, FURTHER INTRODUCING INTO SAID MIXING ZONE A CONCENTRATED REACTIVE GAS IN SUBSTANTIALLY SMALLER VOLUME THAN SAID HEATED GAS, EFFECTING MIXING OF SAID CONCENTRATED REACTIVE GAS WITH SAID HEATED GAS IN SAID MIXING ZONE TO FORM A DILUTED HOT TREATING GAS, FLOWING THE DILUTED HOT TREATING GAS INTO SAID FINAL LAYER AT A RATE SUFFICIENT TO SUSPEND THE SOLID MATERIAL IN SAID LAYER TO FORM A DENSE TURBULENT FLUIDIZED MASS, SEPARATING DILUTE HOT TREATING GAS FROM SAID FINAL LAYER AND FLOWING THE SEPARATED GAS TO THE NEXT HIGHER LAYER TO EFFECT SUSPENSION OF THE SOLID MATERIAL IN SAID LAYER TO FORM A DENSE TURBULENT FLUIDIZED MASS, SEPARATING HOT DILUTE TREATING GAS FROM SAID LAST NAMED LAYER AND SUCCESSIVELY FLOWING THE SEPARATED GAS IN LIKE MANNER TO SUSPEND EACH SUCCEEDING HIGHER LAYER AND FINALLY TO THE FIRST AND HIGHEST LAYER FORMED BY THE CONTINUOUS INITIAL FEEDING OF SOLID MINERAL MATERIALS AND THEREAFTER DISCHARGING SEPARATED GAS FROM SAID HIGHEST LAYER; THE TEMPERATURE OF SAID DILUTED HOT TREATING GAS BEING REDUCED IN FLOWING SUCCESSIVELY THROUGH THE SEVERAL LAYERS WHILE THE TEMPERATURE OF SAID SOLID MATERIAL IS INCREASED PROGRESSIVELY IN DESCENT FROM SAID HIGHEST LAYER TO SAID LOWERMOST LAYER AS A RESULT OF DIRECT HEAT EXCHANGE IN CONTACT BETWEEN SAID DILUTED HOT TREATING GAS AND SAID SOLID MATERIAL; WITHDRAWING THE THUS HEATED AND TREATED SOLID MATERIAL FROM SAID LOWERMOST LAYER OF SAID PRIMARY TREATING ZONE AND CONTACTING THE WITHDRAWN SOLID MATERIAL DIRECTLY WITH CONCENTRATED REACTIVE GAS INTRODUCED AT A TEMPERATURE LOWER THAN THE TEMPERATURE OF SAID SOLID MATERIAL, AND CONCENTRATED REACTIVE GAS BEING FLOWED AT A RATE SUFFICIENT TO SUSPEND THE SOLID MATERIAL THUS CONTACTED IN DENSE TURBULENT FLUIDIZED CONDITION, SEPARATING CONCENTRATED REACTIVE GAS FROM CONTACT WITH SAID SOLID MATERIAL AND ADMITTING THE SEPARATED GAS TO THE AFORESAID MIXING ZONE, CONTINUOUSLY WITHDRAWING SOLID MATERIAL AFTER CONTACT WITH THE CONCENTRATED REACTIVE GAS, CONTACTING THE SOLID MATERIAL THUS WITHDRAWN WITH COOL INERT GAS, ADMIXING COOL INERT GAS WITH REACTIVE GAS TO FORM BY THE ADMIXTURE SAID CONCENTRATED REACTIVE GAS HEREINBEFORE SPECIFIED, AND FINALLY DISCHARGING TREATED SOLID MATERIAL IN COOLED CONDITION. 